The meaning of classification is to group all living organisms into certain groups based on their characteristics. Mainly, the different types of species are separated into 12 groups. They are: mammals, reptiles, insects, amphibians, mollusc, crustaceans, birds, fishes , echinoderms , annelids, myriapods and arachnids.  In this text I will explain the 3 of these groups and their characteristics.


Mammals have five  characteristics. It is very important that the species of mammals have these characteristics. Otherwise, they do not belong with mammals. The first characteristic of a mammals is they have live babies as an example cats do not lay eggs but they give birth to live kittens.

An example of a mammal

As you can see from the example, this cheetah has fur (or hair) which is the second characteristic of a mammal. This characteristic mainly separates mammals from the other 11 groups. However that is not to say that it is the main characteristic.  One of the main characteristics of a mammal is that they feed their young milk that they produced. A common feature mammals have with other groups is that they are vertebrates meaning that they have a back bone.

Human spine

Also, mammals are warm blooded so they prefer warm climates. Most mammals come from land however some can come from the sea.



There are five characteristics of a reptile. One being that they lay eggs; however, the eggs in question are soft so the baby reptiles can easily come out of their shell easily.
Here is a diagram of the reptile shell:


The second characteristic of a reptile is that they are cold blooded. Like mammals, reptiles are vertebrates. However, reptiles have no hair or fur instead they have scales.

Reptiles mainly tend to live on land however they can hold their breath underwater for a while.





Insects are the most common of species. Like all the other groups , insects have 5 characteristics. The first one being that insects are invertebrates. Meaning that they have no spine. Insects are also cold blooded like reptiles. Insects lay eggs and most cannot survive on water. Fun fact on insects they have to have one or two wings.




Thank you for looking at my blog.


An informative blog on classification. Well done, Ofelia.CR

Written By 16ofelia-mai

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